Sero survey in Delhi begins to map exposure to coronavirus
Samples of 20,000 people will be tested by July 10 to ascertain the population-level presence of the IgG antibody, which indicates past infection.Updated: Jun 28, 2020, 05:14 IST
A serological survey began in some parts of Delhi on Saturday to determine the extent of the coronavirus disease (Covid-19)’s spread, even as chief minister Arvind Kejriwal said his government was deploying “five weapons” – testing and isolation, providing oximeters and oxygen concentrators, plasma therapy, screening, and survey – in the fight against the infection.
Blood samples will be taken from randomly selected people as part of the survey, which involves rapid tests for antibodies, to study the scale of undetected infections. Samples of 20,000 people will be tested by July 10 to ascertain the population-level presence of the IgG antibody, which indicates past infection. The activity will take place along with door-to-door screening in the Capital and increased testing for Covid-19.
On Saturday, Delhi began the study in the Central district, which conducted about 700 blood tests. The Capital reported 2,948 Covid-19 cases on Saturday, taking the total infections in the city to 80,188. Delhi has reported 2,558 deaths so far from the infectious disease. The number of fresh cases across the nation surpassed the 20,000 mark for the first time, with 20,179 new infections.
The results of the current study will be used as baseline data and such drives will be conducted periodically to monitor the trend of the infection in the community, according to the training material provided by the National Centre for Disease Control (NCDC), which is spearheading the study. The survey is part of a new Covid-19 response plan prepared by the Delhi health department, in accordance with the recommendations of a committee headed by NITI Aayog member VK Paul. The Centre and the Delhi government agreed on deploying a revamped strategy against the disease in the Capital at a recent meeting chaired by Union home minister Amit Shah.
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Teams of lab technicians and auxiliary nurse midwives (ANMs) posted at government dispensaries and mohalla clinics will visit households and draw blood samples in all 11 districts of the Capital.
On the first day of the survey, the Central district created 30 teams for the exercise, which is also called sero-surveillance. The other districts were in the process of arranging logistics, training the ground staff, and surveying their respective areas to select households.
A senior revenue department official with the Delhi government said on condition of anonymity: “We are in the process of making arrangements and training the staff for it. We have started with the Central district and will scale it up from tomorrow (Sunday). From Monday, it will start in all the districts.”
The New Delhi district, which will collect the lowest number of samples (169) based on the size of its population, will begin the exercise on Monday. The highest number of samples will be collected by the Northwest.
In the East and West districts, the staff that will be deployed for sample collection were being trained on Saturday. “There is a protocol which has to be followed. We have formed close to 25-plus teams, one per dispensary, to carry out the survey. The areas where the teams will go have been finalised as per the guidelines provided to us,” said a senior official with the East district, requesting anonymity.
The exercise is being jointly carried out by NCDC, which functions under the Union health ministry, and the Delhi government. “The serological survey has started from Saturday and will cover 20,000 people. The survey is being conducted door to door and will reveal the extent of coronavirus spread in Delhi,” chief minister Kejriwal said.
He said Delhi was waging a difficult war against the Covid-19 pandemic and will emerge victorious, but it will take time. The Delhi government is combating the pandemic by augmenting hospital beds, increasing the number of tests, providing oximeters and oxygen concentrators to patients in home isolation, providing plasma therapy to patients, and through survey and screening, the CM said.
In the past one month, the number of beds was raised significantly at hospitals and now there was no lack of beds; out of 13,500 available, 7,500 were vacant, he added. Deputy CM Manish Sisodia tweeted: “Sero Testing has been started from today in the fight against Corona in Delhi. Under this, 20 thousand blood sample will be taken from all over Delhi. This test will prove to be very effective in the Delhi government’s campaign against Corona.” Explaining the process of the serological survey, a doctor with the West district said: “Our teams will be sent to 10-15 points or areas identified by us.”
In the North district, five teams have been formed. Each team will have a lab technician, a pharmacist, ANMs and ASHA workers. The teams will be supervised by a doctor, a senior doctor with the district said, asking not to be named. For random selection of the households, each ward in Delhi will be divided into four areas and the households will be selected using a list of homes available with the dispensary in the area. In the absence of such a list, the teams have been directed to stand in the middle of the areas designated to them and identify one household at random. The next household will be selected at an interval of about 5 or 10 houses, according to the methodology. “We have been given a ward-wise break-up of the number of households that have to be included for the study. We have to randomly select these households – for example, if we start from one point of a locality, then we collect samples from house number 1, 5, 10… like that. If a house is locked or people do not consent to be a part of the study, we will move to the next house,” a doctor from the Central district said on condition of anonymity.
At least 30% of the samples from each ward have to be from children (1 to 18 years of age). For the study, only those people who have been living in the city for at least six months will be included.
The teams have to carry a questionnaire (about the health of the participant, travel or contact history), consent forms, blood collection kits, boxes that are used for vaccinations, appropriate personal protective equipment and bags for the disposal of biomedical waste. Each team has to collect up to 40 samples. For every five survey teams, there will be a supervisory team consisting of medical officers from the dispensaries or mohalla clinics, along with an intern or final-year postgraduate student and a nodal officer from NCDC. Earlier this month, the Indian Council of Medical Research revealed the result of its pilot sero-surveillance study of 26,000 people from across India. The overall percentage of general population that was found to have been infected in the past is 0.73%, with urban areas having shown higher Covid-19 prevalence of about 1.09%, the study had revealed.